Treating arterial disease below the knee presents a different set of challenges than working in larger vessels like the iliac or superficial femoral arteries. The tibial arteries that supply the lower leg and foot are considerably smaller in diameter, and disease in this territory is often associated with more advanced peripheral artery disease, frequently including critical limb ischemia. Below-the-knee (BTK) angioplasty has become an important tool for restoring flow in this demanding anatomical territory.
Why Below-the-Knee Disease Is Different
The tibial arteries — the anterior tibial, posterior tibial, and peroneal arteries — are considerably narrower than more proximal vessels, often just a few millimeters in diameter, and they frequently show diffuse, long-segment disease rather than isolated, focal blockages. This pattern is especially common in patients with diabetes, where below-the-knee involvement tends to be more extensive. Because these small vessels supply the foot directly, disease here carries significant implications for tissue viability, which is why BTK intervention is closely associated with critical limb ischemia and limb salvage efforts.
What Happens During a Below-the-Knee Angioplasty?
The procedure generally follows the same basic framework as angioplasty elsewhere in the peripheral vasculature — vascular access, guidewire crossing of the diseased segment, and balloon inflation to restore luminal diameter — but every step is adapted for smaller-scale anatomy. Guidewires and balloon catheters used below the knee are sized specifically for these narrower vessels, and crossing long-segment or heavily calcified tibial disease can require more specialized wire techniques than typically needed in larger arteries. Angiographic imaging throughout the case helps confirm which of the three tibial vessels remain open and guides the operator toward the segment most likely to support wound healing or limb salvage.
Why Small Vessel Balloons Require Careful Selection
Balloon sizing below the knee must be matched precisely to the small native vessel diameter, since oversizing carries a higher relative risk of vessel injury or dissection in such narrow arteries. Extended inflation times are sometimes used in this territory to help achieve an adequate result given the vessels' smaller caliber and tendency toward elastic recoil. Some centers use drug-coated balloon technology below the knee as well, though the evidence base and adoption in this specific territory has evolved somewhat differently than in larger femoropopliteal vessels, and device selection here is guided by the individual patient's anatomy and the treating physician's judgment.
What Determines Success in This Territory?
Because below-the-knee intervention is so frequently performed in the context of critical limb ischemia, success is often measured not just by restored vessel patency but by whether adequate blood flow reaches the specific area needed for wound healing — a concept sometimes described as the angiosome, or direct arterial territory, supplying a given part of the foot. This means the choice of which tibial vessel to treat can be guided by the location of an ulcer or wound as much as by which vessel shows the most severe disease.
Devices Used in Below-the-Knee Intervention
Small-vessel balloon catheters designed for the sizing and length demands of tibial anatomy are part of the toolkit used in BTK intervention, alongside guidewires suited for crossing long or calcified segments. INVAMED's Extender balloon platform, offered across a range of diameters and lengths, is among the devices used across the peripheral arterial disease treatment spectrum; further detail is available on the peripheral arterial disease page, with device selection for below-the-knee anatomy determined by the treating physician.
Does below-the-knee angioplasty always succeed in saving a limb?
Restoring blood flow through angioplasty is one important component of limb salvage, but outcomes also depend on wound care, infection control, and the overall extent of tissue damage present before treatment. A multidisciplinary team typically evaluates all these factors together rather than relying on revascularization alone.
Device availability and regulatory status vary by country. Please contact INVAMED or your authorized local distributor for current regulatory information applicable to your region.